The production of glass filaments for use as insulation by the centrifugal or rotory process is well known. Cobolt, nickel, or iron based superalloys can be employed as the material of the rotor, or centrifuge, with cobalt based and nickel based receiving more widespread use because of their superior properties. For example, see U.S. Pat. Nos. 3,933,484, 3,318,694, 3,010,201, 3,980,473, 3,881,918, 3,806,338, 3,984,240 and 4,203,747.
The requirements for the rotor alloys include high temperature strength and creep resistance as well as oxidation resistance and corrosion resistance to molten glass. Unfortunately, the strongest alloys generally exhibit poor corrosion resistance, and the more corrosion resistant alloys are, as a practical matter, limited to service in the fiberization of traditional insulation forming glasses which generally exhibit a low fiberization temperature, i.e., glasses having a liquidus temperature of less than about 1780.degree. F. and a viscosity of about 316 poise at 2190.degree. F. or less.
Further, some of the present rotors exhibit a 20-40 hour (or more) break-in period. During the break-in period, the fibers produced from such spinners are generally brashy and of low quality. Also, an objectionable amount of dust is produced during the break-in period which, along with the low quality fibers, produce a glass wool mat or pack having a lower thermal resistance than that of a dust free, high quality fiber wool pack.